The present invention relates to radiant heaters and, more particularly, to radiant heaters in which an object to be heated is received within an enclosure.
Radiant heaters have a wide range of uses from paint drying to shrinking heat-shrinkable tubes over wiring bundles or the like. In this latter use, the shrinking of heat-shrinkable tubing, many other methods have also been used. These include using a resistance heating clamp which can be placed around both an elongated object, such as bundle of wires, and a heat-shrinkable tube portion positioned thereover. Another method is based on using a hot air blower which has a stream of hot air emanating therefrom directed by its operator over surfaces of a heat-shrinkable tube previously placed around such a bundle of wires.
Radiant heaters have a number of advantages over the previously discussed methods for heating an object. Radiant heaters rapidly provide energy output after operation thereof is initiated. These heaters can reach operating temperatures, depending on conditions of use, in a typical range of 3 to 7 seconds. Radiant heaters are efficient because the object to be heated is directly heated by impinging infrared radiation without wasteful concurrent direct heating of the surrounding air. In addition, radiant heaters can be made small because the infrared sources typically used provide a relatively high output energy per unit size. A common radiant heating method is to use a radiant heater with a reflector behind the radiation source to direct the energy onto heat-shrinkable tube portions placed around an elongated object with again a concentrated heat directed over the heat-shrinkable tubing.
Previous radiant heaters have a shortcoming in that they are not well suited to heating an object on or very near a surface because of structural limitations about the radiant heating source. Often, there is a need to heat an object, such as bundles of wires or optical fibers, that are on or immediately adjacent a surface. The previous radiant heaters usually do not provide very uniform heating of an object if that object is adjacent a surface. Thus, there is a need to provide relatively rapid and uniform heating of heat-shrinkable tubing over elongated objects.